Financial Information for Guarantor Subsidiaries and Non-Guarantor Subsidiaries (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012	Dec. 31, 2011
Financial Information for Guarantor Subsidiaries and Non-Guarantor Subsidiaries [Abstract]
Parent company's percentage ownership of guarantors (as a percent)	100.00%
Assets
Cash and cash equivalents	$ 78,084	$ 109,015	$ 112,431	$ 104,402
Restricted cash	28,588	30,398
Accounts receivable, net	189,809	209,870
Inventories	67,362	71,255
Notes receivable	10,410	10,298
Other current assets	53,120	53,782
Property and equipment, net	374,108	376,877
Investment in subsidiaries	0	0
Goodwill	781,418	801,373
Intangible assets	94,941	84,291
Intercompany balances	0	0
Other assets	425,463	439,749
Total assets	2,103,303	2,186,908
Liabilities and stockholders' equity
Current installments of long-term debt	10,269	16,458
Other current liabilities	202,955	239,889
Long-term debt, excluding current installments	1,449,122	1,451,708
Other non-current liabilities	131,320	114,062
Intercompany balances	0	0
Stockholders’ equity	309,637	364,791
Total liabilities and stockholders' equity	2,103,303	2,186,908
Parent Company
Assets
Cash and cash equivalents	16,064	27,159
Restricted cash	0	0
Accounts receivable, net	0	0
Inventories	0	0
Notes receivable	10,410	10,298
Other current assets	7,687	9,693
Property and equipment, net	8,317	5,727
Investment in subsidiaries	504,072	520,969
Goodwill	0	0
Intangible assets	0	0
Intercompany balances	48,278	79,735
Other assets	7,554	6,479
Total assets	602,382	660,060
Liabilities and stockholders' equity
Current installments of long-term debt	0	0
Other current liabilities	24,812	28,485
Long-term debt, excluding current installments	250,000	250,000
Other non-current liabilities	17,130	16,784
Intercompany balances	803	0
Stockholders’ equity	309,637	364,791
Total liabilities and stockholders' equity	602,382	660,060
SGI
Assets
Cash and cash equivalents	141	201
Restricted cash	0	0
Accounts receivable, net	61,474	63,944
Inventories	25,627	25,411
Notes receivable	0	0
Other current assets	3,713	3,809
Property and equipment, net	142,998	154,243
Investment in subsidiaries	800,013	802,425
Goodwill	253,928	253,928
Intangible assets	41,649	42,000
Intercompany balances	0	0
Other assets	92,070	74,923
Total assets	1,421,613	1,420,884
Liabilities and stockholders' equity
Current installments of long-term debt	6,280	6,280
Other current liabilities	49,440	58,473
Long-term debt, excluding current installments	1,196,428	1,199,247
Other non-current liabilities	26,208	25,560
Intercompany balances	153,317	136,402
Stockholders’ equity	(10,060)	(5,078)
Total liabilities and stockholders' equity	1,421,613	1,420,884
Guarantor Subsidiaries
Assets
Cash and cash equivalents	0	0
Restricted cash	0	0
Accounts receivable, net	24,212	29,156
Inventories	14,247	16,063
Notes receivable	0	0
Other current assets	7,165	6,773
Property and equipment, net	35,122	32,957
Investment in subsidiaries	0	0
Goodwill	76,741	76,741
Intangible assets	35,441	20,367
Intercompany balances	330,634	302,396
Other assets	9,475	7,507
Total assets	533,037	491,960
Liabilities and stockholders' equity
Current installments of long-term debt	0	0
Other current liabilities	32,470	35,436
Long-term debt, excluding current installments	0	0
Other non-current liabilities	30,522	12,174
Intercompany balances	(245)	0
Stockholders’ equity	470,290	444,350
Total liabilities and stockholders' equity	533,037	491,960
Non-Guarantor Subsidiaries
Assets
Cash and cash equivalents	63,467	82,834
Restricted cash	28,588	30,398
Accounts receivable, net	104,123	116,770
Inventories	27,488	29,781
Notes receivable	0	0
Other current assets	34,555	33,507
Property and equipment, net	187,671	183,950
Investment in subsidiaries	855,801	855,801
Goodwill	450,749	470,704
Intangible assets	17,851	21,924
Intercompany balances	0	0
Other assets	318,979	353,455
Total assets	2,089,272	2,179,124
Liabilities and stockholders' equity
Current installments of long-term debt	3,989	10,178
Other current liabilities	97,828	118,682
Long-term debt, excluding current installments	2,694	2,461
Other non-current liabilities	57,460	59,544
Intercompany balances	225,055	245,748
Stockholders’ equity	1,702,246	1,742,511
Total liabilities and stockholders' equity	2,089,272	2,179,124
Eliminating Entries
Assets
Cash and cash equivalents	(1,588)	(1,179)
Restricted cash	0	0
Accounts receivable, net	0	0
Inventories	0	0
Notes receivable	0	0
Other current assets	0	0
Property and equipment, net	0	0
Investment in subsidiaries	(2,159,886)	(2,179,195)
Goodwill	0	0
Intangible assets	0	0
Intercompany balances	(378,912)	(382,131)
Other assets	(2,615)	(2,615)
Total assets	(2,543,001)	(2,565,120)
Liabilities and stockholders' equity
Current installments of long-term debt	0	0
Other current liabilities	(1,595)	(1,187)
Long-term debt, excluding current installments	0	0
Other non-current liabilities	0	0
Intercompany balances	(378,930)	(382,150)
Stockholders’ equity	(2,162,476)	(2,181,783)
Total liabilities and stockholders' equity	$ (2,543,001)	$ (2,565,120)